Internet GIS and Web mapping have been applied in homeland security, disaster management, business market, transportation, city planning, and K-12 educations. According to a recent research from ComScore Network ((http://www.ebrandz.com/newsletter/2005/July/1july—31july_article1.htm), online map users are a huge market. Currently, Time Warner's MapQuest.com had an estimated 43.7 million U.S. visitors in May 2005, the Yahoo! Maps had 20.2 million users, Google Map had 6.1 million users, and Microsoft's MSN MapPoint had 4.68 million visitors. This is a huge market for mapping services providing more diversified geospatial information services.
The maps presented by these web sites (and other mapping applications) are generated by a map server, a specialized application for the storage and retrieval of map and GIS data. The goal of a map server is to respond to requests for data with as low latency as possible. This requires the optimum use of the host computer's resources, such as memory, network bandwidth and processor usage.
When viewing satellite imagery, categorizing land use data, or comparing the changes of land cover before/after the disasters, traditional GIS applications and Web-based mapping tools can suffer from processing bottlenecks from system overload. This results in slow response times for users making map requests. Map servers attempt to avoid this by mitigating the effect of large image data sizes on the server hardware and client/server communications. Some map servers for generating 3D surface textures decrease the amount of map data in real time through the use of impostors and occlusion culling. This occlusion culling is done by using the current 3D scene viewpoint, which can be inefficient in the use of computer processing and network bandwidth when using a collection of tiles to represent the requested scene. Other techniques for reducing the load on the map server involve caching on either the client or the server end to allow for repeated queries to be fetched without having to search the server's database.
Map servers frequently deal with terabytes of image data. The initial loading of this data into the map server's database is a very computationally intensive process. The image data must be store in such a manner that it can be retrieved quickly when requested. This involves the use of a spatial database, which is a technique for indexing a data set such that it can be queried using physical dimension parameters such as location and spanning range. Loading image data into the spatial database involves intensive image processing operations such as slicing into tiles and pre-processing of data into image pyramids. These lengthy operations require heavy processor and disk utilization, essentially consuming all system resources until the loading is complete.
It is an object of the present invention to provide a graphics processing system and method to obviate or mitigate at least some of the above-mentioned disadvantages.